预应力混凝土连续梁的次内力分析方法

以连续梁为对象,研究了弹性阶段预应力布束形式对结构内力的影响。首先分析了预应力混凝土连续梁中预应力引起的次内力产生的原因,然后把连续梁等效成边跨和中跨2种基本结构形式,将常见预应力束布设形式引起的固端约束次力矩和弯矩用参数表示,包括直线束、局部束、折线形预应力束以及抛物线形预应力束;同时,分析了折线束和抛物线束的梁端压力线与梁重心线的偏离距率及钢束几何形状的对应关系,总结了这2种布束形式对结构内力影响的特征;最后以一个三跨等截面连续梁为实例,对比折线束与抛物线束产生的次内力效应。结果表明,折线束对连续梁的次内力影响远大于抛物线束。该研究结果有助于工程技术人员优化预应力束筋设计。

Analysis Method of Secondary Internal Forces of PC Continuous Beam

With the prototype of continuous beam,authors analyzed the characteristics of prestress impact of diversified arrangements of tendons in elasticity stage.Firstly,authors studied the reasons that results in the secondary internal force were caused by prestressing force in PC continuous beam.Then,authors simplified the continuous bridge to two basic structural type,side-span and mid-span,and provided the secondary torque and bending moment at fix end expressing in parameters for various common arrangements of tendon including straight-line tendon,local tendon,polygonal prestress tendon and parabola prestress tendon.Meanwhile,authors analyzed the corresponding relationship between the distance from pressure line at beam end to gravity center,and the alignment for polygonal and parabola tendons,and summarized the characteristics of prestress impact of polygonal tendon and parabola tendon.Finally,taking a three-span continuous beam as example,authors compared the effects of secondary internal force caused by polygonal tendon and parabola tendon respectively.The results show that polygonal tendon affects the secondary internal force more than parabola tendons.The research offers reference for engineers to optimize the design of prestressing tendons.